@article{4550, abstract = {{We have integrated individual (In,Ga)As quantum dots (QDs) using site-controlled molecular beam epitaxial growth into the intrinsic region of a p-i-n junction diode. This is achieved using an in situ combination of focused ion beam prepatterning, annealing, and overgrowth, resulting in arrays of individually electrically addressable (In,Ga)As QDs with full control on the lateral position. Using microelectroluminescence spectroscopy we demonstrate that these QDs have the same optical quality as optically pumped Stranski–Krastanov QDs with random nucleation located in proximity to a doped interface. The results suggest that this technique is scalable and highly interesting for different applications in quantum devices.}}, author = {{Mehta, M. and Reuter, Dirk and Wieck, A. D. and Michaelis de Vasconcellos, S. and Zrenner, Artur and Meier, Cedrik}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{14}}, publisher = {{AIP Publishing}}, title = {{{An intentionally positioned (In,Ga)As quantum dot in a micron sized light emitting diode}}}, doi = {{10.1063/1.3488812}}, volume = {{97}}, year = {{2010}}, } @article{4551, abstract = {{An intentional positioning of optically active quantum dots using site-selective growth by a combination of molecular beam epitaxy (MBE) and focused ion beam (FIB) implantation in an all-ultra-high-vacuum (UHV) setup has been successfully demonstrated. A square array of periodic holes on GaAs substrate was fabricated with FIB of 30 keV ions followed by an in situ annealing step. Subsequently, the patterned holes were overgrown with an optimized amount of InAs in order to achieve site-selective growth of the QDs on the patterned holes. Under well-optimized conditions, a selectivity of single quantum dot growth in the patterned holes of 52% was achieved. Thereafter, carrier injection and subsequent radiative recombination from the positioned InAs/GaAs self-assembled QDs was investigated by embedding the QDs in the intrinsic part of a GaAs-based p–i–n junction device. Electroluminescence spectra taken at 77 K show interband transitions up to the fifth excited state from the QDs.}}, author = {{Mehta, Minisha and Reuter, Dirk and Melnikov, Alexander and Wieck, Andreas D. and Michaelis de Vasconcellos, Steffen and Baumgarten, Tim and Zrenner, Artur and Meier, Cedrik}}, issn = {{1386-9477}}, journal = {{Physica E: Low-dimensional Systems and Nanostructures}}, keywords = {{Molecular beam epitaxy, Focused ion beam, Self-assembled quantum dot, Electroluminescence}}, number = {{10}}, pages = {{2749--2752}}, publisher = {{Elsevier BV}}, title = {{{Intentionally positioned self-assembled InAs quantum dots in an electroluminescent p–i–n junction diode}}}, doi = {{10.1016/j.physe.2009.12.053}}, volume = {{42}}, year = {{2010}}, } @article{4552, abstract = {{Here we report on investigations on CdSe quantum dots incorporated in ZnSe based Schottky photodiodes with near-field shadow masks. Photoluminescence and photocurrent of individual quantum dots were studied as a function of the applied bias voltage. The exciton energy of the quantum dot ground state transition was shifted to the excitation energy by using the Stark effect tuning via an external bias voltage. Under the condition of resonance with the laser excitation energy we observed a resonant photocurrent signal due to the tunnelling of carriers out of the quantum dots at electric fields above 500 kV/cm.}}, author = {{Panfilova, M. and Michaelis de Vasconcellos, S. and Pawlis, A. and Lischka, K. and Zrenner, Artur}}, issn = {{1386-9477}}, journal = {{Physica E: Low-dimensional Systems and Nanostructures}}, keywords = {{CdSe/ZnSe quantum dots, Photodiode, Quantum confined Stark Effect, Photocurrent, II–VI Semiconductors}}, number = {{10}}, pages = {{2521--2523}}, publisher = {{Elsevier BV}}, title = {{{Resonant photocurrent-spectroscopy of individual CdSe quantum dots}}}, doi = {{10.1016/j.physe.2010.01.013}}, volume = {{42}}, year = {{2010}}, } @inproceedings{7251, author = {{Ishikawa, Atsushi and Oulton, Rupert F. and Zentgraf, Thomas and Zhang, Xiang}}, booktitle = {{Plasmonics: Metallic Nanostructures and Their Optical Properties VIII}}, editor = {{Stockman, Mark I.}}, publisher = {{SPIE}}, title = {{{Extremely low-loss slow-light modes in plasmonic dielectric hybrid systems}}}, doi = {{10.1117/12.860190}}, year = {{2010}}, } @inproceedings{7252, author = {{Sorger, Volker J. and Oulton, Rupert F. and Zentgraf, Thomas and Ma, Renmin and Gladden, Christopher and Dai, Lun and Bartal, Guy and Zhang, Xiang}}, booktitle = {{Plasmonics: Metallic Nanostructures and Their Optical Properties VIII}}, editor = {{Stockman, Mark I.}}, publisher = {{SPIE}}, title = {{{Semiconductor plasmon laser}}}, doi = {{10.1117/12.859136}}, year = {{2010}}, } @article{7494, author = {{Mehta, M. and Meier, Cedrik}}, issn = {{0013-4651}}, journal = {{Journal of The Electrochemical Society}}, number = {{2}}, publisher = {{The Electrochemical Society}}, title = {{{Controlled Etching Behavior of O-Polar and Zn-Polar ZnO Single Crystals}}}, doi = {{10.1149/1.3519999}}, volume = {{158}}, year = {{2010}}, } @article{7496, author = {{Theis, Jens and Geller, Martin and Lorke, Axel and Wiggers, Hartmut and Wieck, Andreas and Meier, Cedrik}}, issn = {{0957-4484}}, journal = {{Nanotechnology}}, number = {{45}}, publisher = {{IOP Publishing}}, title = {{{Electroluminescence from silicon nanoparticles fabricated from the gas phase}}}, doi = {{10.1088/0957-4484/21/45/455201}}, volume = {{21}}, year = {{2010}}, } @article{4153, abstract = {{Nanosphere lithography (NSL) masks consisting of mono- or double-layers of polystyrene (PS) nano-beads are fabricated on silicon exploiting the self-organization of PS particles during the controlled drying of a colloidal suspension on a surface. The shape changes and shrinkage of PS sphere masks upon treatment in an air plasma are studied as a function of initial sphere size, plasma power and treatment time. The influence of several experimental parameters, including the plasma induced temperature rise, are analysed using scanning and transmission electron microscopy. It is demonstrated that a variety of new intriguing nanopatterns can be generated on silicon surfaces by the combination of NSL and plasma techniques, largely broadening the variety of patterns available so far by NSL.}}, author = {{Gogel, D. and Weinl, M. and Lindner, Jörg and Stritzker, B.}}, journal = {{JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS}}, number = {{3}}, pages = {{740--744}}, title = {{{Plasma modification of nanosphere lithography masks made of polystyrene beads}}}, volume = {{12}}, year = {{2010}}, } @article{6619, abstract = {{Strömungsbasierte Mischprozesse sind grundlegender Bestandteil vieler chemischer Prozesse. Realisierbare Mischzeiten reichen von einigen Millisekunden bis zu Sekunden, wobei die vollständige Homogenisierung oft nicht sichergestellt ist. Werden kinetische Parameter chemischer Reaktionen dieses Zeitskalenbereichs ohne Berücksichtigung der Mischprozesse bestimmt, sind sie mischungsmaskiert und geben die inhärente chemische Kinetik nicht wieder. In dieser Arbeit wird die Validierung und Anwendung einer Methode zur Bestimmung inhärenter chemischer Kinetiken von in Flüssigphase ablaufenden chemischen Reaktionen im stationären, laminaren Flachbettmikroreaktor vorgestellt. Der verfolgte Ansatz basiert auf der mechanistischen Modellierung der Molmengen unter Berücksichtigung von Konvektion, Diffusion und Reaktion und der Bestimmung der unbekannten Parameter durch Anpassung des Modells an experimentell ermittelte Konzentrationsverläufe.}}, author = {{Warnecke, H.-J. and Bothe, D. and Zrenner, Artur and Berth, Gerhard and Hüsch, K.-P.}}, issn = {{0009-286X}}, journal = {{Chemie Ingenieur Technik}}, number = {{3}}, pages = {{251--258}}, publisher = {{Wiley}}, title = {{{Modellbasierte Bestimmung lokal gültiger Kinetiken chemischer Reaktionen in Flüssigphase mittels Flachbettmikroreaktor*}}}, doi = {{10.1002/cite.200900169}}, volume = {{82}}, year = {{2010}}, } @article{7993, author = {{Piegdon, Karoline A. and Offer, Matthias and Lorke, Axel and Urbanski, Martin and Hoischen, Andreas and Kitzerow, Heinz-Siegfried and Declair, Stefan and Förstner, Jens and Meier, Torsten and Reuter, Dirk and Wieck, Andreas D. and Meier, Cedrik}}, issn = {{1386-9477}}, journal = {{Physica E: Low-dimensional Systems and Nanostructures}}, number = {{10}}, pages = {{2552--2555}}, publisher = {{Elsevier BV}}, title = {{{Self-assembled quantum dots in a liquid-crystal-tunable microdisk resonator}}}, doi = {{10.1016/j.physe.2009.12.051}}, volume = {{42}}, year = {{2010}}, } @article{39740, author = {{Urbanski, Martin and Kinkead, Brandy and Hegmann, Torsten and Kitzerow, Heinz-Siegfried}}, issn = {{0267-8292}}, journal = {{Liquid Crystals}}, keywords = {{Condensed Matter Physics, General Materials Science, General Chemistry}}, number = {{9}}, pages = {{1151--1156}}, publisher = {{Informa UK Limited}}, title = {{{Director field of birefringent stripes in liquid crystal/nanoparticle dispersions}}}, doi = {{10.1080/02678292.2010.489160}}, volume = {{37}}, year = {{2010}}, } @article{39741, author = {{Kitzerow, Heinz-Siegfried}}, issn = {{0015-0193}}, journal = {{Ferroelectrics}}, keywords = {{Condensed Matter Physics, Electronic, Optical and Magnetic Materials}}, number = {{1}}, pages = {{66--85}}, publisher = {{Informa UK Limited}}, title = {{{Blue Phases: Prior Art, Potential Polar Effects, Challenges}}}, doi = {{10.1080/00150191003683807}}, volume = {{395}}, year = {{2010}}, } @article{39972, author = {{Kitzerow, Heinz-Siegfried}}, issn = {{1439-9598}}, journal = {{Nachrichten aus der Chemie}}, keywords = {{General Chemical Engineering, General Chemistry}}, number = {{6}}, pages = {{678--679}}, publisher = {{Wiley}}, title = {{{33. Arbeitstagung Flüssigkristalle}}}, doi = {{10.1002/nadc.20050530635}}, volume = {{53}}, year = {{2010}}, } @article{39739, abstract = {{ The electrooptic characteristics of the field-induced reorientation of a nematic liquid crystal are studied using graphene layers as transparent conductive electrodes. The covering of a large area with highly conductive graphene was achieved by the thermal reduction of a graphene oxide film. The conductivity of the graphene electrode provides electrooptic properties that are comparable to those of liquid crystal cells with two conventional indium tin oxide electrodes. This result confirms earlier studies and suggestions concerning graphene-based liquid crystal devices. It demonstrates that the fabrication of graphene layers via the deposition and subsequent reduction of graphene oxide is suitable for liquid crystal applications. }}, author = {{Nordendorf, Gaby and Kasdorf, Olga and Kitzerow, Heinz-Siegfried and Liang, Yanyu and Feng, Xinliang and Müllen, Klaus}}, issn = {{0021-4922}}, journal = {{Japanese Journal of Applied Physics}}, keywords = {{General Physics and Astronomy, General Engineering}}, number = {{10R}}, publisher = {{IOP Publishing}}, title = {{{Liquid Crystal Addressing by Graphene Electrodes Made from Graphene Oxide}}}, doi = {{10.1143/jjap.49.100206}}, volume = {{49}}, year = {{2010}}, } @article{39738, author = {{Urbanski, Martin and Kinkead, Brandy and Qi, Hao and Hegmann, Torsten and Kitzerow, Heinz-Siegfried}}, issn = {{2040-3364}}, journal = {{Nanoscale}}, keywords = {{General Materials Science}}, number = {{7}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{Electroconvection in nematic liquid crystals via nanoparticle doping}}}, doi = {{10.1039/c0nr00139b}}, volume = {{2}}, year = {{2010}}, } @article{39737, author = {{Lorenz, Alexander and Schuhmann, Rolf and Kitzerow, Heinz-Siegfried}}, issn = {{0003-6935}}, journal = {{Applied Optics}}, number = {{20}}, publisher = {{The Optical Society}}, title = {{{Switchable waveguiding in two liquid-crystal-filled photonic crystal fibers}}}, doi = {{10.1364/ao.49.003846}}, volume = {{49}}, year = {{2010}}, } @inproceedings{39736, author = {{Kinkead, Brandy and Urbanski, Martin and Qi, Hao and Kitzerow, Heinz-Siegfried and Hegmann, Torsten}}, booktitle = {{SPIE Proceedings}}, editor = {{Khoo, Iam Choon}}, issn = {{0277-786X}}, publisher = {{SPIE}}, title = {{{Alignment and electrooptic effects in nanoparticle-doped nematic liquid crystals}}}, doi = {{10.1117/12.858831}}, year = {{2010}}, } @article{4127, abstract = {{The dynamics of charge and spin injection currents excited by circularly polarized, one-color laser beams in semiconductor quantum wells is analyzed. Our microscopic approach is based on a 14x14 k · p band-structure theory in combination with multisubband semiconductor Bloch equations which allows a detailed analysis of the photogenerated carrier distributions and coherences in k space. Charge and spin injection currents are numerically calculated for [110]- and [001]-grown GaAs quantum wells including dc population contributions and ac contributions that arise from intersubband coherences. The dependencies of the injection currents on the excitation conditions, in particular, the photon energy are computed and discussed.}}, author = {{Duc, Huynh Thanh and Förstner, Jens and Meier, Torsten}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qw}}, number = {{11}}, publisher = {{American Physical Society (APS)}}, title = {{{Microscopic analysis of charge and spin photocurrents injected by circularly polarized one-color laser pulses in GaAs quantum wells}}}, doi = {{10.1103/physrevb.82.115316}}, volume = {{82}}, year = {{2010}}, } @inproceedings{4176, abstract = {{A microscopic theory that describes injection currents in GaAs quantum wells is presented. 14 × 14 band k.p theory is used to compute the band structure including anisotropy and spin-orbit interaction. Transient injection currents are obtained via numerical solutions of the semiconductor Bloch equations. Depending on the growth direction of the considered quantum well system and the propagation and polarization directions of the incident light beam, it is possible to generate charge and/or spin photocurrents on ultrashort time scales. The dependence of the photocurrents on the excitation conditions is computed and discussed.}}, author = {{Duc, Huynh Thanh and Förstner, Jens and Meier, Torsten}}, booktitle = {{Ultrafast Phenomena in Semiconductors and Nanostructure Materials XIV}}, editor = {{Song, Jin-Joo and Tsen, Kong-Thon and Betz, Markus and Elezzabi, Abdulhakem Y.}}, keywords = {{tet_topic_qw}}, pages = {{76000S--76000S--9}}, publisher = {{SPIE}}, title = {{{Microscopic theoretical analysis of optically generated injection currents in semiconductor quantum wells}}}, doi = {{10.1117/12.840388}}, volume = {{7600}}, year = {{2010}}, } @article{24980, abstract = {{We discuss transport and localization properties on the insulating side of the disorder dominated superconductor-insulator transition, described in terms of the dirty boson model. Analyzing the spectral properties of the interacting bosons in the absence of phonons, we argue that the Bose glass phase admits three distinct regimes. For strongest disorder the boson system is a fully localized, perfect insulator at any temperature. At smaller disorder, only the low temperature phase exhibits perfect insulation while delocalization takes place above a finite temperature. We argue that a third phase must intervene between these perfect insulators and the superconductor. This conducting Bose glass phase is characterized by a mobility edge in the many body spectrum, located at finite energy above the ground state. In this insulating regime purely electronically activated transport occurs, with a conductivity following an Arrhenius law at asymptotically low temperatures, while a tendency to superactivation is predicted at higher T. These predictions are in good agreement with recent transport experiments in highly disordered films of superconducting materials.}}, author = {{Gögh, N. and Thomas, P. and Kuznetsova, I. and Meier, Torsten and Varga, I.}}, issn = {{0003-3804}}, journal = {{Annalen der Physik}}, number = {{12}}, pages = {{905--909}}, title = {{{Localization of excitons in weakly disordered semiconductor structures: A model study}}}, doi = {{10.1002/andp.20095211219}}, volume = {{18}}, year = {{2010}}, }